The Synthesis Development of High Hardness and High Nitrogen Containing ta-CNx coating

Abstract

In this study, we aimed to establish a method for depositing high-nitrogen-content and high-hardness ta-CNx coatings. The two different nitrogen mixing process to add them in tetrahedral amorphous carbon (ta-C) was conducted. The nitrogen ion introduction methods are the gas introduction method where nitrogen gas is directly introduced to the arc source created near the carbon target as a nitrogen ion introduction, and the nitrogen ion beam irradiation method towards the coating substrate direction. The results showed that in both deposition methods, an increase in the N/C ratio led to a decrease in hardness. In the ion beam method, although the N/C ratio could be increased to about 0.21 at 40 sccm, the coating hardness decreased to approximately 12 GPa. On the other hand, with the gas supply method, at 40 sccm, the N/C ratio was approximately 0.17, lower than the ion beam method, but the hardness achieved approximately 20 GPa. When the deposition was carried out with the specimen temperature rise suppressed to below 60°C, supplying nitrogen gas directly to the arc source to introduce nitrogen into the coating resulted in maintained the hardness even with an increase in N/C ratio from 0.10 to 0.17, maintaining it at about 32 GPa. In contrast, with the ion beam method, an increase in N/C ratio from 0.12 to 0.17 led to a decrease in hardness from approximately 32 GPa to a minimum of about 20 GPa.